Centrifugal switch



y w. 2. WEST, JR, ETAL 2,441,914

CENTRIFUGAL SWITCH Filed Feb. 26, 1946 Mor giza [Gamble Gum/nu,

Patented May 18, 1948 UNITED PATENT OFFICE ,GENTRIFUGAL SWITCH -WillisZ. West, -Jr., and Morgan F. Gamble, Winston-Salem, N. C.

Application February 26, 1946, Serial No. 650,352 ;9, Clai ms.- (Cl. 200-80) wherein terminalsare electrically connected by a conducting liquid such as -mercury, when the rotor is at rest or is moving slowly and breaks the. electrical connection, when the speed of rotation of such rotor increases.

A further. object of the inventionis to provide a. device-of the above mentioned characten-which is extremelysimple in construction and is a completelyassembled unit, .which. may be readily installed-in place, without-thenecessity of making adjustments, requiring the services of a skilled attendant.

A further objector the invention is to provide a deviceof the .above mentioned character, which will operate properly-When mounted upon the armature shaft.;-of a motor, regardless-of the angular position that the device lassumesupon the shaft.

Afurther object of the invention isto provide a device of the above mentioned character which may be installed upon a horizontalorvertical shaft.

Other. objects and advantages: of the invention will, be apparent duringthev course. of the-following description.

In theaccompanying drawings forming a part of this applicationand in :WhiChlikG 'IlUD'lBIBJS are employed to designatexlike parts, throughout the same,

,Figurel is-a perspective view of a switch embo yi my i ention,

Figure 2 ;is an :end elevation of the same, I Figure 3 ;is a central vertical: longitudinal section through thedevice, 1

' Figure-.4; is a. vertical section taken on line.- 4-4 bfi g e sleeves H,- formedofeopperior-the llke. These rings or elongated sleeves have a press fit upon the sleeve [0 andtheir outer ends preferably terminate flush with the outer ends of the sleeve l0. Therings-orelongated sleeves H are prefer- I ably of thesame length and their inner ends are spaced forming an annular passage [2. This annular passage leads into an annular groove;l2', disposedat the longitudinal center of the sleeve I0. This groove or chamber I2 is formed in an annular housing or body portion l3, formed of insulatingmaterial, such as fiber, plastics or the like, The housing 13 has end openings [4, for

receiving the inner; ends of the rings or elongated sleeves, having a driving fit therein, so that the housing is rigidly secured to the rings or elongated sleeve H to rotate therewith and a liquid tight joint is effected. The housing l3 has a'port -l5,to be covered by a removable plug Hi, and this port leads into the annular groove or chamber l2. This chamber is preferably ,U- shapedin cross-section, with its large open side arranged next to the passage l2 and in free communication therewith. The groove I2 receives an electrical conducting liquid, such as mercury l8. This mercury is fed into thegroove through the port l5. The elements l0, II and i3 are rigidly connectedand rotate as a unit. The numeral l9 designates brush holders, which are slidably mounted upon the rings or elongated sleeves -ll, Each brush holder comprises ,an annular hub 20, slidably receivingthe ring or elongated sleeve H, which is rotatable therein. Each hub has a radial tubularv arm 2!, haVing-a bore 22, which is preferably square in crosssection for-receiving a brush or carbon 23, which is also square in cross-section. This brush has a concave facel l, to properly contact with the ring II. The brush23 is forced inwardly by a spring 25, carrying a'contact disc 20 at its outer end-connected with-a wire 21, connected at its inner .end to the brush 23. A terminal plug 23 .screws into the cylindrical bore 29 of the arm 2! and contacts with the disc 26 and therefore has electrical connection with the brush. The terminal plug 28 carries the usual binding post 30'. The annularhubzfi is provided opposite to the tubular arm with a radial arm 30,- and these arms have openings, transversely arranged for receiving a screwilL This screw is clamped to thearms by nuts3l. Astrap 32 is secured to the screw ',3l, as shown, and'may be attached to a stationary part 33', for holding the connected brush; holders against turning movement.

Theoperation ofthe device is as follows:

The sleeve I0 is suitably rigidly applied'to the horizontal armature shaft 33 of a motor and rotates therewith. This motor is of the split phase type, or may be of the capacitive type. The split phase type motor has a starting stator winding and a running stator winding. As is well known, in starting a motor of this type, current is first supplied to the starting and running stator windings, and when the motor speeds up current is cut off from the starting stator winding. The present switch is employed to supply current to the starting stator winding to start the motor and to cut the current off when the motor speeds up. When the motor is at rest, the mercury I8 is accumulated in the bottom of the annular groove l2 and has a sufficient level so that it contacts with the lower portions of the rings H, thus closing the circuit between these rings and supplying current to starting stator winding. As the motor speeds up, the unit including the rings II has its speed of rotation correspondingly increased, and the mercury is thrown outwardly by centrifugal force and moves to the outer surface of the groove l2. forming a shallow ring of mercury, out of contact with the rings I I. The circuit is then broken between these rings.

Our device is an entirely self contained unit, as all parts are permanently assembled, when the sleeve is applied to the armature shaft. The strap 32 is then secured to the stationary part 33', and the wires connetced with the binding posts 30', This is practically all the adjustments which need be made, and these do not require the service of a skilled electrician, It is immaterial what angular positions the brush holders have with respect to the rings ll, Since the contacts or brushes 23 are exteriorly of the housing l3, there is no tendency for the device to short circuit across the inner ends of the rings or elongated sleeves l l, due to carbon dust. Further, the contacts or brushes 23 are covered, and there is very little, if any, liability of flying sparks being produced, due to improper contact between the brushes and the rings, if improper contact should occur. By virtue of the tubular hubs 2!) slidably engaging the rings l l, these rings are kept clean, for proper contact with the brushes 23, and the device is self cleaning. The device is extremely simple and formed of few parts, not liable to derangement.

We also contemplate providing a device for use upon a' vertical armature shaft 33*. This device is shown in Figure 6. The sleeve Ill is now mounted upon the vertical armature shaft 33, to rotate therewith. A housing I3 is provided, having an annular groove 35. This annular groove has inclined top and bottom walls 36 and 31, which lead into the annular space Ill. The housing I3 is otherwise identical with the housing I3. All other parts of the device are identical with those shown and described in connection with the first form of the invention, except that the sleeve I0 and rings II are vertical and the housing l3 and brush holders 20 are horizontal.

When the vertical armature shaft 33 is at rest, the mercury 38 gravitates to the bottom of the groove 35 and has a sufilcient level to electrically connect the upper and lower rings ll. When the motor speeds up, the mercury is acted upon by centrifugal force and travels outwardly and upwardly, breaking contact .with the lower ring II or both upper and lower rings II. It is thus seen that this device may be employed to supply current to the starting stator winding, when the motor startsQand will cut oif this current when the motor speeds up.

It is to be understood that the form of our invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size, and arrangement of parts, may be resorted to, without departing from the spirit of our invention or the scope of the subjoined claims.

Having thus described our invention we claim:

1. A centrifugal switch comprising axially arranged opposed elongated metallic sleeves having their inner ends disposed near each other and spaced for providing a, passage, means to connect the elongated sleeves and insulate the same, an insulating housing mounted upon the inner ends of the elongated rings and having a liquid tight connection therewith and covering the passage between the inner ends of the sleeves, said housing having a substantially annular recess in communication with said passage, the elongated sleeve extending axially and outwardly beyond the ends of the housing, mercury held within the annular recess brush holders arranged outwardly of the housing adjacent to their ends and slidably mounted upon the outer portions of the sleeves, and brushes carried by the brush holders and engaging the sleeves.

2. A centrifugal switch comprising an insulating sleeve, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends arranged near each other and spaced to provide a substantially annular passage, an insulating housing mounted upon the inner ends of the elongated sleeves and covering the substantially annular passage and having a substantially annular recess in communication with such passage, the rings extending axially and outwardly beyond the ends of the housing, mercury held within the substantially annular recess, brush holders disposed exteriorly 0f the housing adjacent to its ends and having openings to rotatably receive the outer portions of the elongated sleeves, and brushes carried by the brush holders for engagement with portions of the elongated sleeves which are covered by the brush holders.

3. A centrifugal switch comprising an insulating sleeve, elongated metallic contact sleeves mounted upon the insulating sleeve having their inner ends arranged near each other and spaced to provide a substantially annular passage, an insulatin housing mounted upon the inner ends of the elongated metallic sleeves and covering the substantially annular passage and having a substantially annular recess in communication with such passage, the outer portions of the elongated metallic sleeves extending axially and outwardly beyond the ends of the insulating housing, mercury held within the substantially annular recess, brush holders arranged exteriorly of the housing and adjacent to the ends of the housing and having hubs provided with recesses for rotatably receiving the outer portions of the elongated sleeves, tubular arms carried by the hubs and having bores which lead into the openings of the hubs, brushes mounted within the tubular arms to contact with the elongated sleeves, resilient means to move the brushes inwardly, and means connecting the hubs and serving to hold them in place upon the elongated sleeves.

4. A centrifugal switch comprising an insulating sleeve, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends arranged near each other and spaced to provide a substantially annular passage, an insulating housing mounted upon the inher ends of the elongated sleeves and covering the annular passage and having an annular recess in communication with such passage, brush holders arranged exteriorly of the housing adjacent to its ends and including hubs having openings to rotatably receive the outer portions of the elongated sleeves, said brush holders having radial openings which extend to the openings of the hubs, brushes mounted Within the radial openings to contact with the elongated sleeves and covered by the hubs, resilient means to move the brushes inwardly, generally radial arms carried by the hubs, and means to connect the generally radial arms.

5. A centrifugal switch comprising an insulating sleeve, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends arranged in close relation and spaced to provide an annular passage, an insulating housing mounted upon the inner ends of the elongated sleeves and covering the passage and having an annular recess in communication with such passage, the elongated sleeves eXtending axially and outwardly beyond the housing, insulating brush holders disposed outwardly of the insulating housing adjacent to its ends and having openings to rotatably receive the outer portions of the elongated sleeves, the brush holders serving to clean the outer portions of the elongated sleeves, brushes mounted within the brush holders to contact with the elongated sleeves, extensions carried by the brush holders, a pin connecting the extensions, and a strap secured to the pin.

6. A centrifugal switch comprising an insulat ing sleeve adapted to be mounted upon a shaft for rotation therewith, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends arranged near each other and insulated from each other, an insulating housing mounted upon the inner ends of the contact sleeves to rotate therewith, the outer ends of the contact sleeves extending axially and outwardly beyond the ends of the insulating housing, centrifugally operated contact means mounted within the housing for oo-action with the inner ends of the contact sleeves, brush holders having openings to rotatably receive the outer end portions or the contact sleeves and covering such outer portions and serving to clean such outer portions by contact therewith, and brushes carried by the brush holders to contact with the contact sleeves.

7. A centrifugal switch comprising a horizontal insulating sleeve to be mounted upon a rotatable shaft, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends arranged near each other and insulated from each other, a vertical insulating housing mounted upon the inner ends of the contact sleeves and having an annular recess, mercury held within the annular recess, vertical brush holders having openings to rotatably receive outer ends portions of the contact sleeves which project outwardly beyond the vertical housing, brushes carried by the brush holders and en gaging the contact sleeves, and means to hold the brush holders against turning movement.

8. A centrifugal switch comprising a vertical insulating sleeve to be rotated, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends insulated, a

horizontal insulating housing mounted upon the inner ends of the insulating rings and having an annular recess which is vertically inclined outwardly in an upward direction, horizontal insulating brush holders arranged above and below the housing and having openings to rotatably receive the contact sleeves, mercury held within the annular recess, brushes carried by the brush holders, and means connecting the brush holders.

9. A centrifugal switch comprising an insulating sleeve to be rotated, elongated metallic contact sleeves mounted upon the insulating sleeve and having their inner ends arranged near and insulated from each other, an insulating housing mounted upon the inner ends of the contact sleeves for rotation therewith, the contact sleeves extending axially and outwardly beyond the housing, centrifugally operated contact means mounted within the housing for co-action with the inner ends of the contact sleeves, brush holders having openings to rotatably receive the outer end portions of the contact sleeves and disposed adjacent to the opposite ends of the housing, the

, brush holders having generally radial openings leading to their contact sleeve receiving openings, brushes arranged within the generally radial openings, binding posts mounted upon the brush holders, springs to move the brushes toward the contact sleeves, the binding posts and brushes being electrically connected, and means to prevent the brush holders moving axially from the insulating housing, the arrangement being such that the insulating housing covers the ininner ends of the contact sleeves so that a short circuit cannot occur at such inner ends due to carbon dust and the brush holders clean the outer end portions of the contact sleeves by engagement therewith and enclose the brushes.

WILLIS Z. WEST, JR.

MORGAN F. GAMBLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

